I’ve got my printed copy of Operation Unfathomable now, and I think I’d like to explore the Unfathomable Underworld… The module itself is a gonzo funhouse that runs like a subterranean wilderness trek. In tone, I think it would mesh well with my previous DolmenBarrow campaign, and I think I’ll set it in an different region of the same game world. (Perhaps also associated with Dwimmermount?)
Rules System: I would use Labyrinth Lord, modified with the house rules that I’ve used before. Players would begin with new PCs (a primary character with 2,501 XP and a secondary with 1,251 XP), but I would definitely need to tweak my old character creation guidelines.
Operation Unfathomable seems pretty human-centric. This would mean some restrictions to demihuman races:
I don’t see a place for Moss Dwarves, Grimalkin, or Half-Goats in OU, but I think Gnomes and Lumpen-Ones would fit. Elves are rare in the underworld, but there could be some Eld-related shenanigans afoot. Blue Dwarves are replaced by Robo-Dwarves with an inexplicable taste for herd-animal milk rather than booze. Grey Dwarves are Tinker Gnomes. (“Gnome Insurgency” sounds better.)
Robo-Dwarves and Tinker Gnomes will not be permitted as PCs until they’re “unlocked” during campaign play.
Oh; and I’ll need to make a LL version of the Wooly Neanderthal class, likely based on the Feral Dwarf.
One thing that I know I want to change is the Underworld Ranger. In my campaign, they follow the guidelines for the Ranger class from the Advanced Edition Companion (AEC), with the following changes:
- Underworld Rangers receive their damage bonus against creatures of Chaos (instead of goblins and giants).
- They save as AEC Rangers, but gain +2 on saving throws against Chaos effects. (No special bonus vs. spells.)
- At 1st level, Underground Rangers get the Underworld Survival ability (from Operation Unfathomable) and Underworld Tracking. They have a base 65% chance of tracking in wilderness and a base 90% chance when underground (the reverse of AEC Rangers).
- They receive Special Equipment as described in Operation Unfathomable (including Requisition Item at 4th level).
- They do not gain druid spells, magic-user spells, or the ability to employ unusual magic items.
In other respects, Underworld Rangers are identical to AEC Rangers. Ability score requirements are INT 12, WIS 12, CON 15. They get the improved AEC HD progression (2d6 at 1st level) and follow the standard Ranger XP table. They have the same restrictions on carrying treasure (with donations to the Underground Ranger Service) and hiring henchmen (all subcontractors must be approved by the URS).